[seqfan] A056619

israel at math.ubc.ca israel at math.ubc.ca
Tue Feb 21 21:49:05 CET 2017

A056619 is "Smallest prime with primitive root of n or 0 if no such prime 
exists." In the Crossrefs (what should probably be a Comment) says:

Here the primitive root may be larger than the prime, whereas in A023049 in 
may not be.

and the Comment says:

a(n) = 0 only for perfect squares, A000290.  

The Data has a(n) = 0 for squares < 99.

Well, I agree with that for even n, because if p is an odd prime a square 
can't be a primitive root mod p. But I see no reason for that to be true 
for odd n: all odd numbers, including odd squares, are primitive roots mod 
2. So I think a(n) should be 2, not 0, for odd squares.

However, this being an old sequence, I hesitate to change the Data.  What do
you suggest?


More information about the SeqFan mailing list